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Smelly job that requires the skills of city's highly trained engineers


    Smelly job that requires the skills of city's highly trained engineers


    Field technicians from Shanghai Environmental Monitoring Center collect gas samples. 

    People are usually attracted to fragrances like those from flowers or cooking. However, there is a group of people whose job it is to follow evil and even poisonous smells.

    They are called the “smell panelists,” and they are actually highly trained engineers at Shanghai Environmental Monitoring Center.

    Garbage dumps and chemical plants are the most common workplaces for the panelists, who are sent in to collect smelly gas samples that are then taken to the monitoring center and mixed with clean air before undergoing a "discriminant test."

    The test will be undertaken by six panelists, whose judgment over the density of the smelly gas will be used in evidence of any charges brought against polluters or used for other evaluation purposes.

    Being a panelist is a kind of part-time job for our engineers, who are usually working in the laboratories or other departments of the center,” said Chen Xiaoting, an engineer at Shanghai Environmental Monitoring Center. Chen arranges the shifts for the panelists.

    Chen told Shanghai Daily that there are usually two kinds of missions – to evaluate the polluting matters of certain enterprises under the authority’s request, or to make a raid on pollutant discharges following tip-offs.

    “To collect the gas sample is the most laborious part. Sometimes our field technicians have to spend a whole day at a certain spot, suffering the heat and displeasing smells,” said Chen.

    Wind speed and direction are factors that need to be taken into consideration when choosing spots for gas collection.

    “We need to pick two or three spots for each mission. At each spot, three jars of air samples are collected. But there should be a two-hour interval between every two collections.”

    Holding a vacuum container, a field technician has to stand still for at least a minute to have the jar filled. The samples will be taken back to the monitoring center for the discrimination procedure, which has to be completed within 24 hours.

    “We will dilute the smell sample by 10 times and blow it into an airbag. At the same time, we will prepare another two bags of clean air. A panelist will have to smell them and pick out the smelly one,” said Chen.

    “Six panelists will work at the same time. There will be three air bags for each panelist in each round, and they are not allowed to communicate with each other during the procedure. In the second round, the gas samples will be further diluted by 100 times. Coming to the third round, the smell would usually become too thin for some to distinguish. The results are collected after each round and will be calculated by the computer for a final report.”

    “Panelists who smell the samples cannot be the same technicians who collected it so as to ensure the accuracy of the result,” Chen added. “If one knows in advance what kind of smell it is, it will affect his or her judgment.”

    Asked why the discrimination procedure cannot be completed by machines, Chen said the formation of smelly gas is too complicated.

    “The smell is usually created by sulfur compounds, nitrogenous compounds and compounds consist of carbon, hydrogen and oxygen. Currently, machines can only test the density of limited types of substances, while nose remains the most reliable weapon. This is also international practice.”

    Both field technicians and panelists have to go through exams to acquire a certificate to qualify to do the job. They have to be aged from 18 to 45, dont smoke and be free of olfactory diseases. In the exam, they have to distinguish five smells representing flowers, sweat, excrement, sweet rice crust and fruit.

    “The certificate is valid for three years. Also, a panelist cannot eat any smelly food like onions or garlic before working, neither should one use perfume or cosmetics,” Chen said.

    Wei Huajun, director of Shanghai Environmental Monitoring Center, said there are about 80 engineers at Shanghai Environmental Monitoring Center who hold the panelist certificate.

    “One of the most frequently asked questions is whether the job would harm the panelists’ health as the gas samples might be poisonous sometimes.

    “The samples are diluted so the risk is largely reduced. Also, the panelists take turns so that they won’t be exposed to the smells on a frequent basis.”